He downs the last few drops of his carajillo (a mean coffee/brandy combo, more rocket fuel than alcohol), rolls his eyes back down into their sockets and does something unbelievably, impossibly, incomprehensibly un-Super-Furry-Animals-like. His band may well have had a big tank, they may indeed play new psychedelia and it's highly likely that they do in fact enjoy the odd magic mushroom, but laughing? This isn't the Gruff Rhys we'd been expecting at all…

The tail end of 1999 is a rum old time to come to Bilbao. After 14 months of peaceful cease-fire, the Basque separatist guerrilla group ETA has returned to the politics of violence. So far, ETA are believed to be responsible for the deaths of over 800 people during their 30-year battle for Basque independence from the Spanish and French governments. This weekend, that figure may well increase, and visiting the biggest city in the region suddenly seems a supremely daft thing to be doing.

Still, Super Furry Animals are famed for doing daft things. Leaving aside the gloriously twisted oddness of their music, there's that tank for starters, with its ear-shredding sound system and its tour of British festivals a few summers back. Then there are those 40-foot inflatable bears they travelled with to promote their Radiator album two years ago. And, even now, there lurks a Welsh-language album called Mwng on the horizon, and an as-yet-untitled album of instrumental techno set to follow. Which might not be daft, but it sure as hell ain't normal.

Except it is. Sort of. For this lot. Who are also enormously, abnormally normal, wackety-spackety japes aside. Singer/guitarist Gruff Rhys, guitarist Huw "Bunf" Bunford, bassist Guto Pryce, keyboard player Cian Ciarán and drummer Dafydd "Daf" leuan make up the most lovably normal, thoughtful and wide-eyed band I've met for years.

"If we come up with an idea," hums Gruff, as we munch down some tapasin the spindly side streets of Bilbao's old quarter, while the others soundcheck across town, "we don't worry about being perceived as fools. We just do it anyway, celebrate life, do something fantastical instead of being cowardly. But fucking hell! There's so much more we could do."

Welcome, then, to three pages in the company of the Sanest Band In Britain. There's a hell of a lot more to this bunch than tanks and gimmicks, you know…

The first thing you notice about Gruff Rhys is how slowly he speaks. An illustration? Well, after only 15 minutes' conversation, The Maker's MiniDisc recorder has skipped all the way through to track 58, recognising each one of Gruff's eternal pauses as another gap between the songs it's used to recording, "I know I come across as quite slow," he fumbles, swilling each syllable around his mouth before spitting it out. "I take time to put my sentences together, so I'm sometimes perceived as being fucking bonged off my head. And I'm not!"

So why do you speak like that, Gruff?

"It's just genes, innit?" he shrugs, picking at a slice of Spanish omelette. "My brother talks the same way, so I don't consider myself to be strange. And after I've had a few pints I can talk really quickly — I just don't know what the fuck I'm talking about! But I'm not slow and I'm not thick. I just think about things all the time. I question everything."

What kind of things?

"Well," he frowns, looking down at his watch, which hasn't told the correct time for months now. "I always think about whether we're living in a time of advancement or decline. People talk a lot about mad, technological futures, but it's a really amazing time to be around now. We should be making the most of all this technology which people take for granted, 'cos it might not be available one day. All the technology in my house broke down on the same day recently: my telly, my video, my watch, everything. It didn't matter whether it was connected to the National Grid or powered by battery — it all failed. And also my back packed in! It was really weird. I don't know what happened!

"If I was a paranoid person," he blinks, finishing off his food, "that'd really freak me out. Maybe central Cardiff was hit by a large dose of radiation!"

Time for a quick photo shoot, so we hop in a cab and head for Bilbao's amazing Guggenheim Museum, a monstrously beautiful aluminium flower lying like a just-crashed spaceship by the city's docks.

"It's fan-tas-ti-cal!" coos Gruff delightedly, as we're met by the other Super Furries, their tour manager and countless Spanish children who scamper around our feet like over-affectionate pets. "But I think that's what we're trying to do as a band. The Guggenheim's not weird, it's just fucking amazing! And we're nonconformist, too, but all we want to do is make exciting, accessible achievements."

Which is something Super Furry Animals are looking forward to now even more than ever, what with the recent fate of their label, Creation.

"It's fucking great," insists a frankly hammered Cian, prising an omnipresent beer can away from his mouth long enough to slur a sentence or two [SFA have been on the road for months now and alcohol numbs the tedium]. "Were we upset? Naaaaaah, it was almost a relief."

"It was slowly dying," nods Daf. "Everything was getting fucked up and Creation was definitely not the company we joined four years ago."

"But this is the most exciting time ever for the band!" enthuses Gruff. "Even though Creation supported us brilliantly for years, the possibilities are endless now."

Any regrets?

"Well, I wish they'd put Wherever I Lay My Phone (That's My Home) out as a single. It's based on the same Nokia ringtone as that Jimmy Cauty Christmas record, so we can hardly put it out now, can we? Bastard! I quite fancied the idea of a novelty hit, too!

"I just like the idea of creating cultural havoc in our time," he adds as the last rays of winter light glint off the Guggenheim's metallic shell and into his eyes. "In a positive way."

It's showtime, and there's a distinct sense of excitement as the band set off for the venue.

"What do we bring to a town when we play?" wonders Gruff, winding through Bilbao's darkening streets in the back of a taxi. "Good tunes and profanity! Hopefully inspiration. I like the idea that, when you come to a town, you're bringing a vibe with you. Me and Bunf were in Paris doing interviews in the summer and the record company bought us tickets to see the Beach Boys, who were playing that night. But the only original Beach Boy in the band was Mike fucking Love and we started to feel such bad Mike Love vibes all around the city we had to book a flight to Amsterdam that night! We couldn't handle being in the same country as him! So, hopefully, we bring good vibes. Hopefully, we're the anti-Mike Loves."

Gruff huddles down under the hood of his parka and giggles. "He's got this solo album called Mike Love Not War, you know!"

Super Farry Animals' (sic) show at the Gwendolyne Club in the Getxo suburb of Bilbao is indeed anti-Mike-Love-ular. Despite that misspelling on their posters, a significant number of locals have spurned the opportunity to see Ocean Colour Scene across town and come to hear renditions of their new single, the fiercely optimistic Do Or Die, the astonishingly chorused Hometown Unicorn and the intoxicatingly romantic The Turning Tide. Yeah, you heard. Not weird, not arch, not even the tiniest bit elitist or indulgent. Just plain old romantic.

"It's a romantic idea to be in a band in the first place," suggests Gruff, shuffling about the band's food-filled dressing-room-cum-banqueting-hall after the show, "A few years ago, I was quite a functional human being. I used to think: 'I don't want to be a twat pop star!' But it is magical how you can be with your mates, get on a bus and make records that get played on the radio to loads of people. It's superb, but we laugh at it as well. We go: 'Fucking hell! We're in a pop band! Shit!'

"What I hate, though, is sentimentality," he adds, uncorking one of several rather fine bottles of local Rioja that tonight's promoter has brought along, "I hate Eric Clapton singing a song about his son dying and making a million dollars off of it. I think that's sick — total lowest-common-denominator, sentimental crap and an insult to the boy. So I'm gonna start getting Bambi on people. Some of our songs are a bit Bambi-like songs like [previous single] Fire In My Heart, but that was written absolutely sincerely. It's sincere sentimental crap."

Gruff's not strange, but he's by no means your average pop star material either. Born of farming stock ("That's why I'm so tall. Frankly, androgyny's out of the question!"), he was raised by his former poet mother and his vigorously political father, a man who campaigned all his life for Welsh rights, language and culture. If you wonder why the Super Furries continue to write occasional songs in Welsh, despite the obvious commercial disadvantages, you need look no further.

Gruff's speech slows even further when the subject is raised and he starts absent-mindedly rearranging things from disorder into order.

"He… um, my dad died a few months ago," he stammers, toying with a teaspoon until it stands dead straight in its pot of sugar. "So that was… well, shit. It was only a few days before the first Welsh Parliament for over 500 years. My dad spent his life campaigning for that — it was his main thing in life. And he didn't even see it. He knew it was coming, but he didn't get to vote. So that's been a big cloud over my year."

Later, as we drive back to town past the snowy peaks which dominate Bilbao's horizon ("It reminds me of Bangor," sighs Daf), Gruff adds: "There's something about mountains. My dad wrote guide books about climbing mountains — some of my earliest memories are of being shoved in a rucksack, strapped to his back and taken up cold mountains, occasionally sticking my head out of the bag, thinking, 'Fuck this!' and sticking it back in! It was quite traumatising!"

He stares expressionlessly out of the window. "It's part of what's formed me as a person. As a kid, I used to live right underneath this mountain, I'd escape up it when I was little, climb up 3,000ft and hide from the world."

The next morning, and Super Furry Animals are hangover-dying at the tiny local airport, waiting for a flight to speed them back to London to shoot the video for Do Or Die. As Bunf pores over the Athletic Bilbao goodies in the airport shop and Daf lines up vodka and oranges for all-comers, Gruff looks out at the runway nervously.

"I was just thinking about whether they were gonna bomb the airport!" he confesses. "It's sad what's happening here, because the people all seem to be into peace. It's good to respect your culture, but not to become obsessed by the power and the glory of it. I just see parallels with how I grew up here, with what was drummed into me as a kid — the realities of growing up speaking a language that's considered a minority interest."

And this coming from a man whose last album (our Number Three album of '99, remember) was called Guerrilla?

"Yeah," he shrugs, "but Guerrilla was just a cheap pun on Super Furry Animals. And, to make sure nobody read any crass, militaristic statements into it, we used the subtitle 'Non-violent Direct Action'. Which is arguably the best way to achieve what you're trying to do in any kind of a struggle. What kind of struggles are we interested in? Well, advanced capitalism is destroying Earth, it's destroying all culture as we know it. People will have to make choices: do they want to be part of that machine or do they want to help to slow that machine down?"

But you're well and truly a part of that capitalist machine, pal.

"Oh, absolutely," he nods, vigorously. "That's human nature — people have always bought and sold. But the multinational companies are more powerful now than sovereign states. They're just interested in accumulating more and more money and power, and I really don't think they need it all. But I'm not a politician. I'm a musician. I'd make a terrible politician — I am diplomatic, but I'm obsessed by melody and rhythm and frequencies and… can I say 'poetry' without sounding like a twat?"

Feel free. Are SFA a poetic band then?

"Well," he hums as the flight is finally called, "we don't claim to write poetry, I've written some terrible lyrics, you know! Do Or Die is a political cliché set by Gandhi, so it's a dumb pop song that five-year-olds can jump up and down to, singing Gandhi lyrics! I define myself against bloated rock wankers like Jim Morrison: humourless and self-important. He thought he was a poet, but he was rubbish. And Robert Plant, another really pompous fool. He thought he was sexy, writing horrible songs about laydeeez: 'Baby, baby, baby… Whoaaaah!'I've never had a pair of leather trousers in my life!"

Looking at the band as they huddle together, waiting to board the plane, one thing becomes strikingly clear. Far more than your Oasises, your Suedes, your Supergrasses, your Charlatans and your Blurs, Super Furry Animals really do look bulletproof, as if nothing could ever split them up.

"We just don't take the concept of a band seriously," muses Gruff. "If you try to represent a certain lifestyle or look or image, you're fucked. It's rubbish! No five people really wanna dress the same, unless they're in the fucking army!

"But I wouldn't want to work with anyone else," he smiles with certainty. "And anyway, we're doing pretty good, aren't we? We earn more than nurses, we travel the world a few times a year, we get to make the albums of our dreams and play to thousands of people on a global level. Our attitude is that we want to record all the time, do everything now. Because we're only here now and you never know what'll happen tomorrow. That's our attitude."